The History of Our Tribe Hominini Textbook Part I An Introduction to Paleoanthropology Chapter 3 Primate Evolution

. Primate Evolution Figure Anthropoid Evolution by Taylor . While we have no primate fossil material prior to the Epoch , the first primates are thought to have evolved prior to the Epoch ( possibly as far back as 90 , during the Late . With the extinction of the dinosaurs at the end of the Cretaceous , many terrestrial niches became available and predation pressures were somewhat relaxed . In addition , temperatures were higher than in the recent past ( see Figure ) and the ( flowering plants ) were undergoing an adaptive radiation , relatively rapid speciation , and spreading globally . The spread of flowering plants resulted in an adaptive radiation of insect pollinators and herbivores ( as well as insectivorous and arboreal vertebrates . The earliest primates likely descended from a small , nocturnal , insectivorous mammal . The tree shrews and ( also known as flying lemurs ) are the closest living relatives to primates . The tree shrew is used as a living model for what the earliest primates , or primate predecessors , might have been like . At some point , primates or their ancestors moved into the trees and adapted to an arboreal environment . Two theories regarding the evolution of some primate characteristics , such as grasping or prehensile hands , oriented eyes , and depth perception , are the Arboreal and Visual Predation Theories . The Arboreal Theory posits that primate characteristics , such as grasping hands and feet and the presence of nails instead of claws , are the result of moving into and adapting to an arboreal environment . Imagine the casualties ! The Visual Predation Theory asserts that characteristics that were to scurrying around in trees and visual features in particular , such as convergent orbits , are adaptations to insect predation . Short of a net , grasping hands , visual acuity , and depth perception are essential for catching insects , but I guess they would be kind of handy for using a net as well ! While primates are thought to have evolved in Asia , the majority of the early fossil material is found in North America and Europe , dating to the Epoch ( The map in Figure indicates both living 23

Polar Ocean Equivalent AT ( A ' to Optimum I My ' 9200 65 Million Years 33 ' 39 of Climate Change Ja . 60 I 40 30 20 Millions of Years Ago 50 Figure Temperature change over time . 65 Climate Change by Robert is licensed under . Notes Pal , Ol , Mia , and ( Primates Sire Figure Primate phylogeny . Primate phylogeny from in Wikipedia is licensed and fossil sites . They are divided into two , and . In eral , the were diurnal , animals that are thought to be the ancestors of the primates , the lemurs of Madagascar and the of Africa and Southeast Asia ( and of Africa and of Southeast Asia ) see Figure ) The smaller , nocturnal are good candidates for the ancestors of . However , due to the early dates for ancestral , it is possible that the and were sister lineages . 24 The History of Our Tribe

Figure Tree shrew . 050917 mane by is licensed under . Figure Range of living primates ( green ) and fossil sites ( Teal ) Extent range with fossil sites , a derivative work by , is in the public domain . During the Epoch , the early primates experienced an adaptive radiation and expanded into numerous niches over a broad geographic area . The northern expansion of early primates into Europe and North America was possible because and North America were joined as the large landmass known as and , as mentioned , it was warm enough for tropical animals to move into northern latitudes . Due to subsequent global cooling , the early primates in North America and Europe went extinct . primates spread into Africa after it docked with . They are also hypothesized to have on floating mats of vegetation to Madagascar , where they evolved into the great diversity of extinct and extant lemur species . Primate Evolution 25

HANK ! AND AH ! AND MONKEYS . Gorilla , 13 , 14 , 15 . Macaque 19 , Baboon 21 , 22 , Figure Hands of apes and monkeys . Hands and Feet of Apes and Monkeys by Richard is in the public domain . 26 The History of Our Tribe Figure . Notes Top left lemurs ( Madagascar ) top right sifaka ( Madagascar ) top middle left ( Madagascar ) top middle right ruffed lemur ( Madagascar ) bottom middle left mouse lemur ( Madagascar ) bottom middle right slow loris ( Asia ) bottom left slender loris ( Asia ) bottom right greater ( Africa ) By at least the late , the first anthropoid primates had evolved . There is debate over the origin of the , the ancestor of the monkeys and apes . There are four different theories of our try , each with its share of supporters ( tarsier , or ( independent origin as yet undiscovered . Remains of early dating to the late are found in Africa and Asia . A stem or basal anthropoid , meaning the original ancestor of all monkeys and apes , comes from the deposits of China . Termed genus ( see Figure ) it was as small as the smallest living anthropoid , the pygmy marmoset monkey of South America . While lemurs have striped tails , I do not know of any other striped primates so am not sure why the artist gave them stripes but it sure is an intriguing little creature ! Other late fossils have been discovered in ( genus ) Thailand ( genus ) Libya ( genus ) Algeria , and the Beds of Egypt . During the Epoch ( the anthropoid primates underwent a great adaptive radiation . The richest location for anthropoid fossils is the Beds of Egypt . are divided into three families , and , from most primitive to most derived over time . The New World monkeys are thought to have branched off from the , with which they share some characteristics . Genus is a prime contender for a possible ancestor . Once again , a rafting hypothesis is proposed for the migration of that ancestor from Africa to South . The ancestors of the Old World monkeys and apes diverged from the family . The , also known as ) is thought to be a common ancestor of the ape and Old World monkey lineages ( see Figure ) While the earliest were . Primate Evolution 27

Figure . Illustration by Taylor . more than , the apes ( or ) were the first to successfully adapt to changing conditions in Africa . 28 The History of Our Tribe Figure or . by Nobu is licensed under . Figure Proconsul by is licensed under . For years , people have asked me , Barbara , you do really believe that we came from monkeys , do you ?

and I always answered , No , we came from apes ! However , our common anthropoid ancestor was more than So , YEAH , I suppose I do ! During the Epoch ( the adaptive radiation of the apes or can be observed in the fossil record . The earliest fossils are from Kenya and . There were 20 or more genera of apes during the and they exhibited a wide range of body sizes and adaptive strategies . Proconsul is a possible stern ape , dating to ( see Figure and ) The ancestry of the lesser apes is unclear but they are thought to have branched off . The great apes diversified and spread from Africa to Asia and Europe . The ancestors of the orangutans , the , moved into western and subsequently eastern Asia . Remains in Turkey have been dated to 14 . The largest primate that ever lived , the now extinct genus ( known only from isolated dental and mandibular fragments ) also had a ancestry . Dryopithecine apes moved into Europe during the late . Generally referred to as dental apes , due to the scanty remains of jaws and teeth , that evolutionary side branch eventually went extinct due to global cooling , as with the earlier in the northern latitudes . While there were Old World monkeys in the Epoch , such as genus from Kenya , the adaptive radiation of the Old World monkeys lagged behind the . However , the same . Primate Evolution 29

conditions that drove most ape genera to extinction in Africa led to an explosion of monkey species . Monkeys could more quickly adapt due to their shorter life stages and greater number of offspring . A baboon can give birth every two years versus four or five years for gorillas and chimps , respectively . While the ancestor of the stayed in the trees , the ancestor of the or cheek pouch monkeys , such as macaques and baboons , adapted to traveling on the ground as well as in the trees . The ability to exploit both arboreal and terrestrial resources expanded their niche and they survived and thrived in Africa and Asia . With only two extant genera , the African did not diversify to the same extent , having been confined to forests . However , the Asian did not experience the same forest loss as their African cousins did and are thus much more diverse . When African forests later expanded , the ancestors of some species , such as the colorful arboreal , went back to the trees . It has been difficult to trace the origin of the gorilla lineage during the due to a paucity of fossils from that time and many conflicting viewpoints . Some of the contenders for the stem African great ape are ( 10 ) and ( from Kenya . Other ble ancestors or related species are ( and ( 15 ) from Kenya and ( 13 ) from . The chimp and human lineages are thought to have diverged by the late . Global cooling in the latter part of the led to the extinction of all ape genera in northern latitudes . Forest cover in Africa was vastly reduced over time due to climatic fluctuations and while most apes went extinct , the newly emerged thrived . experienced an adaptive radiation during the Epoch ( and late in the Epoch ( kya ) our own species , Homo , evolved ( 5200 kya ) a , Figure Proconsul by Taylor . 30 The History of Our Tribe